Copper carbonate is green and copper oxide is black. You can see a colour change from green to black during the reaction. The carbon dioxide produced can be detected using limewater, which turns milky.
Under favorable conditions, some ammonia may oxidize to nitrate. Phosphorus, potash, and various micro-nutrients are also essential for biological growth. These are normally present in more than adequate amounts in compostable materials and present no problem.
During composting a great deal of energy is released in the form of heat in the oxidation of the carbon to C0 2. For example, if a gram-molecule of glucose is dissimilated under aerobic conditions, to kilogram calories kcal of heat may be released.
Oxidation at thermophilic temperatures takesplace more rapidly than at mesophilic temperatures and, hence, a shorter time is required for decomposition stabilization.
The high temperatures will destroy pathogenic bacteria, protozoa microscopic one-celled animals , and weed seeds, which are detrimental to health or agriculture when the final compost is used.
Aerobic oxidation of organic matter produces no objectionable odor. If odors are noticeable, either the process is not entirely aerobic or there are some special conditions or materials present which are creating an odor. Aerobic decomposition or composting can be accomplished in pits, bins, stacks, or piles, if adequate oxygen is provided. Turning the material at intervals or other techniques for adding oxygen is useful in maintaining aerobic conditions.
This temperature can also be maintained for several days before further aeration. The heat necessary to produce and maintain this temperature must come from aerobic decomposition which requires oxygen.
After a period of time, the material will become anaerobic unless it is aerated. It requires a considerable amount of oxygen and produces none of the characteristic features of anaerobic putrefaction. In its modern sense, aerobic composting can be defined as a process in which, under suitable environmental conditions, aerobic organisms, principally thermophilic, utilize considerable amounts of oxygen in decomposing organic matter to a fairly stable humus.
Decomposition of organic material in the compost pile depends on maintaining microbial activity. Any factor which slows or halts microbial growth also impedes the composting process.
Efficient decomposition occurs if aeration, moisture, particle size, and a sufficient source of carbon and nitrogen are in evidence. Oxygen is required for microbes to decompose organic wastes efficiently. Some decomposition occurs in the absence of oxygen anaerobic conditions ; however, the process is slow, and foul odors may develop.
Because of the odor problem, composting without oxygen is not recommended in a residential setting unless the process is conducted in a fully closed system see plastic bag method under Composting Structures.
Mixing the pile once or twice a month provides the necessary oxygen and significantly hastens the composting process. A pile that is not mixed may take three to four times longer to decompose.
Raising the pile off the ground allows air to be drawn through the mass as the material decomposes. Coarse materials should be placed on the bottom as the pile is built or placed in the pile and removed after the decomposition starts. The more oxygen, up to at least percent, the more quickly the biodegradation will take place.
Adequate moisture is essential for microbial activity. A dry compost will not decompose efficiently. Proper moisture encourages the growth of microorganisms that break down the organic matter into humus.
If rainfall is limited, water the pile periodically to maintain a steady decomposition rate. Add enoughwater so the pile is damp but not soggy. Avoid over watering. Excess water can lead to anaerobic conditions which slow down the degradation process and cause foul odors. If the pile should become too wet, turn it to dry it out and restart the process.
Grinding the organic material before composting greatly reduces decomposition time. The smaller the size of the organic refuse particle, the more quickly it can be consumed by the microbes. A shredder is useful for chipping or shredding most landscape refuse and is essential if brush or sticks are to be composted. A low-cost method of reducing the size of fallen tree leaves is to mow the lawn before raking.
Wind-rowing the leaves into long narrow piles one foot high will make the shredding process more efficient. If the mower has an appropriate bag attachment, the shredded leaves can be collected directly.
However, grinding is entirely optional. Temperature of the compost pile is very important to the biological activity taking place.
Low outside temperatures slow the activity down, while warmer temperatures speed up decomposition. These high temperatures will help destroy weed seeds and disease organisms within the pile.
There are many organisms that breakdown organic materials. Most are not seen by the human eye, but they are there throughout the process.
Others that are large enough to see, are usually associated with the later breakdown stages. The most important organisms in the breakdown process are the bacteria. The bacteria present in any given pile are dependent upon the raw material present, amount of air in the pile, moisture conditions of the pile, pile temperature and numerous other factors.
Compostable organic materials normally contain a large number and many different types of bacteria, fungi, molds, and other living organisms. Only very limited data are available regarding the variety of different organisms and their specific functions. It appears that more species of bacteria are involved in aerobic decomposition than in anaerobic putrefaction. Although many types of organisms are required for decomposition of the different materials, the necessary variety is usually present in the materials to be composted, and the organisms thrive when environmental conditions are satisfactory.
During decomposition, marked changes take place in the nature and abundance of the biological population. Some of the many species will multiply rapidly at first but will dwindle as the environment changes and other organisms are able to thrive under more varied conditions. Temperature and changes in the available food supply probably exert the greatest influence in determining the species of organisms comprising the population at any one time. Aerobic composting is a dynamic process in which the work is done by the combined activities of a wide succession of mixed bacteria, actinomycetes, fungi, and other biological populations.
Since each is suited to a particular environment of relatively limited duration and each is most active in decomposition of some particular type of organic matter, the activities of one group complement those of another. The mixed populations parallel the complex environments afforded by the heterogeneous nature of the compostable material.
Except for short periods during turning, the temperature increases steadily in proportion to the amount of biological activity until equilibrium state of balance with subsequent heat losses is reached, or the material becomes well-stabilized humus-like. In aerobic composting bacteria, actinomycetes, and fungi are the most active. Thermophilic fungi usually appear after 5 to 10 days, and actinomycetes become prominent in the final stages, when short duration, rapid composting is accomplished.
Except in the final stages of the composting period, when the temperature drops, actinomycetes and fungi are confined to a sharply defined outer zone of the stack, 2 to 6 inches in thickness, beginning just under the outer surface. Some molds also grow in this outer zone. The population of fungi and actinomycetes is often great enough to impart a distinctly grayish white appearance to this outer zone. The sharply defined inner and outer limits of the shell in which actinomycetes and fungi grow during the high temperature active composting period are due to the inability of these organisms to grow at the higher temperatures of the interior of the pile.
Browns are the carbon-rich yard clippings, such as dead leaves, branches and twigs. A carbon-to-nitrogen ratio between 25 to 1 and 30 to 1 is ideal for rapid composting, according to the University of Illinois. Microorganisms feed on both carbon and nitrogen. The carbon gives the microorganisms energy, much of which is released as carbon dioxide and heat, and the nitrogen provides additional nutrition to continue growing and reproducing.
If there is too much carbon in the compost pile, decomposition occurs at a much slower rate as less heat is generated due to the microorganisms not being able to grow and reproduce as readily, and therefore not able to break down the carbon as readily. On the other hand, an excess of nitrogen can lead to an off-putting ammonia smell and can increase the acidity of the compost pile, which can be toxic for some species of microorganisms.
Proper moisture is also vital for the health of the microorganisms that help with the composting process. A moisture content between 40 and 60 percent provides enough dampness to prevent the microorganisms from becoming dormant but not enough so that oxygen is forced out of the pile. The amount of oxygen within the compost pile is also important as an oxygen deficit leads to anaerobic microorganisms taking over, and that can lead to a stinky compost pile.
Oxygen can be added into the compost pile by stirring or turning over the pile. Note: The USDA recommends burying food waste if using an open-composting pile to deter unwanted pests looking for a free meal, such as flies, rodents and raccoons.
Commercial composting companies also collect products such as paper carry-out containers for food and compostable dinnerware and flatware that are specifically labeled BPI Certified Compostable.
Dairy products, eggs, meat products and fats are typically not recommended for the composting pile, but there are many larger commercial composting facilities that are well-suited for dealing with the smells and pathogens that may exist in these products. To help with the more complex waste, livestock manure is often added to commercial composting sites to help increase the heat and the rate of composting.
According to North Dakota State University , livestock manure from herbivores , including cows, sheep and goats, already contains a high amount of nitrogen and many of the aerobic microorganisms that are essential to composting. In outdoor systems, compost invertebrates survive the thermophilic stage by moving to the periphery of the pile or becoming dormant. Regulations by the U. As the compost begins to cool, turning the pile usually will result in a new temperature peak because of the replenished oxygen supply and the exposure of organic matter not yet thoroughly decomposed.
After the thermophilic phase, the compost temperature drops and is not restored by turning or mixing. At this point, decomposition is taken over by mesophilic microbes through a long process of "curing" or maturation. Although the compost temperature is close to ambient during the curing phase, chemical reactions continue to occur that make the remaining organic matter more stable and suitable for use with plants. The temperature at any point during composting depends on how much heat is being produced by microorganisms, balanced by how much is being lost through conduction, convection, and radiation.
Through conduction , energy is transferred from atom to atom by direct contact; at the edges of a compost pile, conduction causes heat loss to the surrounding air molecules. Convection refers to transfer of heat by movement of a fluid such as air or water. When compost gets hot, warm air rises within the system, and the resulting convective currents cause a steady but slow movement of heated air upwards through the compost and out the top.
In addition to this natural convection, some composting systems use "forced convection" driven by blowers or fans. This forced air, in some cases triggered by thermostats that indicate when the piles are beginning to get too hot, increases the rates of both conductive and convective heat losses. Much of the energy transfer is in the form of latent heat -- the energy required to evaporate water.
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